Surah 34. Saba, Ayah 17

Neither the Qur'an nor any authentic hadith tells us anything definite about the way in which the people of Sheba had sinned at the time immediately preceding the final collapse of the Dam of Ma'rib (i.e., in the sixth century of the Christian era). This omission, however, seems to be deliberate. In view of the fact that the story of Sheba's prosperity and subsequent catastrophic downfall had become a byword in ancient Arabia, it is most probable that its mention in the Qur'an has a purely moral purport similar to that of the immediately preceding legend of Solomon's death, inasmuch as both these legends, in their Qur'anic presentation, are allegories of the ephemeral nature of all human might and achievement. As mentioned at the beginning of note [23] above, the story of Sheba's downfall is closely linked with the phenomenon of men's recurrent ingratitude towards God. (See also verse {20} and the corresponding note [29].)

Kafur: intensive form: "those who deliberately and continuously reject Allah and are ungrateful for His Mercies, as shown by their constant wrong-doing.